Factorizing Simple Expressions


Goal when Factorizing Expressions

Given expressions that are being added or subtracted, the goal of factorizing is to separate out the largest possible common factor. This can be useful to simplify fractional expressions, to better view the contents of an expression, or to aid in solving equations.


Method for Factorizing Expressions

Given an expression such as
6a3 b2 8a4 b4,

the following are the general steps for its factorization:


Step 1: Reduce all numbers to their prime factorization.
 

2·3·a3 b2 − 2·2·2·a4 b4

 

Step 2: Expand all exponential expressions.
 

2·3·a·a·a·b·b − 2·2·2·a·a·a·a·b·b·b·b

 

Step 3: Find numbers and variables that are common to all expressions.
 

2·3·a·a·a·b·b2·2·2·a·a·a·a·b·b·b·b

The largest possible set of these is called the Greatest common factor (GCF)
 

GCF = 2·a·a·a·b·b

 

Step 4: Isolated the GCF in each expression.

2·a·a·a·b·b (3) − 2·a·a·a·b·b (2·2·a·b·b)

Step 5: Use the distributive law to move the GCF outside being sure to place  parentheses around what remains.

2·a·a·a·b·b (3 − 2·2·a·b·b)

Note: The expression is now factorized however it is good form to write the final factorization in exponential form.
 

2·a3 b2(3 − 22 ·a2)

 

Step 6: Check the solution

2·a3 b2(3 − 22 ·a2) = 2·a3 b2(3) − 2·a3 b2(22 ·a2)

               = 6a3 b2 23 a4 b4

                              = 6a3 b2 8a4 b4


 


Example #1

Factorize

12a b2 c3 8b3 c + 4a4 b c2


Step 1: Reduce all numbers to their prime factorization.
 
2·2·3·a b2 c3 − 2·2·2·b3c + 2·2a4 b c2

 

Step 2: Expand all exponential expressions.
 
2·2·3·a·b·b·c·c·c − 2·2·2·b·b·b·c + 2·2·a·a·a·a·b·c·c

 

Step 3: Find the GCF.
 
2·2·3·a·b·b·c·c·c2·2·2·b·b·b·c + 2·2·a·a·a·a·b·c·c,

GCF = 2·2·b·c

 

Step 4: Isolate the GCF in each expression.
 
2·2·b·c·(3·a·b·c·c) − 2·2·b·c·(2·b·b)+ 2·2·b·c·(a·a·a·a·c)

 

Step 5: Use the distributive law to move the GCF outside being sure to place  parentheses around what remains.
 
2·2·b·c·(3·a·b·c·c − 2·b·b + a·a·a·a·c)

Note: The expression is now factorized however it is good form to write the final factorization in exponential form.
 

4bc·(3abc2 2b2 + a4 c)

 

Step 6: Check the solution

4bc·(3abc2 2b2 + a4 c) = 4bc·(3abc2) − 4bc·(2b2) +4bc·(a4 c)

                         = 12ab2 c3 8b3c + 4a4bc2

 

 


Example #2

Factorize
9x3 y2 z 3xyz + 6x2 y3 z


Step 1: Reduce all numbers to their prime factorization.
 
3·3·x3 y2 z − 3·xyz + 2·3 x2 y3 z

 

Step 2: Expand all exponential expressions.
 
3·3·x·x·x·y·y·z − 3·x·y·z + 2·3·x·x·y·y·y ·z

 

Step 3: Find numbers and variables that are common to all expressions.
 
3·3·x·x·x·y·y·z3·x·y·z+ 2·3·x·x·y·y·y ·z

then the GCF is

GCF = 3·x·y·z

 

Step 4: Isolated the GCF in each expression.
 
3·x·y·z(3·x·x·y) − 3·x·y·z(1)+ 3·x·y·z(2·x·y·y)

 

Step 5: Use the distributive law to move the GCF outside being sure to place  parentheses around what remains.
 
3·x·y·z(3·x·x·y − 1+ 2·x·y·y)

Note: The expression is now factorized however it is good form to write the final factorization in exponential form.
 

3xyz(3x2 y + 2x·y2 − 1)

 

Step 6: Check the solution

3xyz(3x2 y + 2x·y2 − 1)= 3xyz(3x2 y ) + 3xyz(2xy2) 3xyz(1)

              = 9x3 y2 z + 6x2 y3 z 3xyz

                  = 9x3 y2 z 3xyz + 6x2 y3 z